Single data rate (SDR) memory is a type of memory where data is only captured on a positive clock edge. SDR memory is generally fully synchronous and utilizes an internal bus at the same width as an external bus. SDR memory operates to have memory accesses at the clock speed of the memory.
Double data rate (DDR) memory is a high speed memory that reads and/or writes data at double the clock speed. DDR memory has an internal data bus twice the width of an external data bus. Compared with single data rate memory, DDR memory can provide about twice the performance for similar clock speeds and power consumption.
In order to correctly read and write memory device in the smaller period, a DDR memory control device with data strobe calibration function is crucial.